Limits for Horizontal Wood Diaphragm Deflection

[smokiibear]

Would someone kindly point me in the direction of where limits are located for Horizontal Wood Diaphragm Deflection. I see how to calculate diagraphm deflection with EQ 23-1 in 2305.2.2, but I don't seem to be able to locate limiting criteria.

Thanks, for your help.

 

[msquared48]

Might try contacting the APA to see if they have any guidance on the matter.

The old plywood diaphragm design manuals from the APA that I have merely state that wood walls will tolerate more lateral deflection from the diaphragm than masonry or concrete walls. Not really much help as they are putting the limitation for deflection on the wall design.

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[NITTANYRAY]

I am assuming that you are dealing with a fairly long building.
If that is the case the allowable drift at the top of the wall near the center of the building may be your limiting criteria. h/180 is usually a good limitation for deflection in the vertical plane.

 

[smokiibear]

Actually, I'm looking at cantilevering a diaphragm per 2305.2.5, which requires diaphragm deflection analysis under the exception. However, no limit is provided.

 

[southard2]

The limit will be set by the allowable drift limit of your walls. You can usually find this in various chapters of your building code such as masonry, steel, etc... I agree with the above posting that H/180 to H/200 is a resonable range for most buildings.

Also in some codes the span to width ratio of a horizontal wood diaphragm is 4:1.

John Southard, M.S., P.E.

http://www.pdhlibrary.com